Finding the Fourth Proportional to 1,258.38, 1,886.40 and 641.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,258.38 : 1,886.40 = 641.61 : x
2. Step 2: Convert to fraction form
   1,258.38/1,886.40 = 641.61/x
3. Step 3: Cross multiply
   1,258.38x = 1,886.40 × 641.61
4. Step 4: Simplify right side
   1,258.38x = 1,210,333.10
5. Step 5: Solve for x
   x = 1,210,333.10/1,258.38
6. Step 6: Final answer
   x = 961.82